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The Endocrine System
Chapter 18
Comparison of NS and ES, table 18.1

Nervous & Endocrine Systems coordinate functions
of all body systems: the neuroendocrine system
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________________________
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nerve impulses conducted along axons of neurons
at synapse nerve impulses trigger release of mediator
molecules = _____________________
_______________________
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releases mediator molecules = ________________
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molecules leave glands  blood
circulating blood delivers hormones to virtually all cells
hormones affect only cells with the proper receptor
Comparison of control by NS & ES
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Nervous system
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Neurotransmitters
Act close to release site
Muscles, glands, neurons
Onset of action within
milliseconds
Duration of action is
generally brief
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Lasting milliseconds
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Endocrine system
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Hormones
Act far from release site
Cells throughout body
Onset of action: seconds
to hours, to days
Duration of action is
generally longer
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Lasting second to days
Exocrine vs. Endocrine
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______________________
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Exocrine glands secrete products into ducts that carry
secretions into:
 Body cavities
 Into the lumen of an organ
 Outer surface of the body
Sweat, oil, mucous, digestive
______________________
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Endocrine glands secrete products (hormones) into interstitial
fluid surrounding secretory cells rather than ducts
 From interstitial fluid blood(or directly to)  target cells
Fig.18.01
Functions of hormones
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Help ________________:
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fig 18.1
Chemical composition & volume of internal environment
(interstitial fluid)
Metabolism and energy balance
Contraction of smooth & cardiac muscle fibers
Glandular secretions
Some immune system functions
____________________________
Regulate reproductive system
Help establish ____________________
Hormones
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___________- secretion of endocrine cells, alters
physiological activity of ______________
approximately 50 hormones
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Hormones travel through body in the blood
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each affects only a few cell types
cell will only respond if has specific receptor for hormone
have powerful effects in low concentrations
bind receptors on target cell
various target cells respond differently to same hormone
If excess hormone present, receptors may  =
_______________________
Circulating vs. local hormones
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_____________________- most endocrine
are this type, circulate in the blood
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From secretory cells  interstitial fluid  blood
_______________- act on neighbor or same
cell that secreted it, without entering blood
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________________- beside or near
________________- self
Fig.18.02
Response to hormone
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Various target cells–
______________________________________
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Ex.) insulin:
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stimulates synthesis of glycogen in liver cells
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stimulates synthesis of triglycerides in adipose cells
Responses are:
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_____________________
_______________________________
_______________________________ in or out
_________________________
_________________________
Chemical classes of hormones, table 18.2
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____________________
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Steroid hormones- derived from cholesterol
Thyroid hormones- T3 and T4
Nitric oxide (NO)- hormone and neurotransmitter
____________________
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Amine hormones- catecholamines, histamine, seratonin,
melatonin
Peptide hormones- some have carb glycoprotein
hormones
Eicosanoid hormones- important local, may circ
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prostaglandins
leucotrienes
Lipid soluble
fig. 18.3
Water soluble
Figure 18.4
Control of secretion
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Release usually in ________________
Regulation __________________ production
Hormone secretion regulated by:
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______________________________
______________________________
______________________________
Most regulation works by feedback loops
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Negative feedback loop, 18.17
Positive feedback loop, 1.4
Negative feedback
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Ex.) Glucocorticoids
Positive feedback
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Ex.) Oxytocin
Hypothalamus & pituitary gland, 18.5
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___________________- “master” endocrine gland
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secretes hormones that control other endocrine glands
__________________- major link between NS & ES
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important regulatory center in NS- can control pituitary
crucial endocrine gland
 Cells of hypothalamus synthesize 9 different hormones
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2 of these are stored and secreted from the posterior pit.
Anterior pituitary secretes 7 hormones
Together these16 hormones play important roles in
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Hypothalamus endocrine function
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At least 9 hormones synthesized by hypothalamus
5 releasing & 2 inhibiting hormones produced affect
_____________________ (___________________)
 produced by hypothalamic neurosecretory cells
 transported within axon & released from axon
terminals
 diffuse hypophyseal portal system 1° 2° plexus
 target cells of anterior pituitary
GHRH, GHIH, TRH, GnRH, PRH, PIH, CRH
Hypothalamic function (2)
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Neurosecretory cells w/cell body in hypothalamus
synthesize the 2 hormones that __________________
______________ (___________________) where the
axon terminals lie
 package into secretory vesicles
 travel to axon terminal and stored
 released from posterior pituitary due to nerve
impulse triggering exocytosis  capillary plexus
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Oxytocin and Anti-diuretic hormone (ADH)
Regions of the pituitary gland
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Anterior pituitary -75% of total wgt of gland
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Posterior pituitary – only oxytocin and ADH
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Pars distalis, pars tuberalis- sheath around infundibulum
Adeno= ________, hypophysis = __________________
Secretes hormones that reg. wide range
 release _______________________ & suppressed
______________________________________
 controlled by negative feedback loops
Contains axons & axon terminals of >10,000 neurons from
nuclei in hypothalamus
 Terminals associated w/ pituicytes- specialized neuroglia
Pars nervosa, infundibulum
________________________________________________
Pars media = atrophies during fetal development
Hypophyseal portal system
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_______________________- blood flows from one
capillary network into portal vein & then to 2nd
capillary network without passing thru heart
Hypophyseal portal system- blood flows from
capillaries in hypothalamus into portal vein that
carries blood to capillaries of adenohypophysis
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Neurosecretory cells synthesize releasing & inhibiting
hormones in cell bodies  vesicles  axons  1° plexus
Act immediately on anterior pituitary before diluted or
destroyed in general circulation
5 releasing hormones of hypothalamus
table 18.3
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Growth hormone releasing hormone (GHRH) =
somatocrinin
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Thyrotropin releasing hormone (TRH)
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Stimulates gonadotrophs
Prolactin releasing hormone (PRH)
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Stimulates thryotrophs AND lactotrophs
Gonadotrophic-releasing hormone (GnRH)
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Stimulates somatotrophs
Stimulates lactotrophs
Corticotropin-releasing hormone (CRH)
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Stimulates corticotrophs
2 inhibiting hormones of hypothalmus
table 18.3
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Growth hormone Inhibiting hormone (GHIH)
= Somatostatin
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released from hypothalamus inhibits activity of
somatotrophs
Prolactin Inhibiting hormone (PIH) =
dopamine
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inhibits activity of lactotrophs
Cells of the Anterior Pituitary
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____________________ – “somato” = body,
“tropin” = change
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secrete ___________________________ (hGH) or
somatotropin
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Stimulates several tissues to secrete insulin-like growth
factors
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general body growth
regulate metabolism
___________________ - secrete thyroid
stimulating hormone (TSH) or thyrotropin
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controls secretions & activities of thyroid gland
Cells of the anterior pituitary (2)
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_______________-- “gonado” = seed
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Secretes _________________________ (FSH)
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Stimulates estrogen production in ovaries
Initiates oocyte development
Sperm production
Secretes _________________________ (LH)
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Stimulates secretion of progesterone & estrogen in
ovaries
Stimulates ovulation, formation of CL
Stimulates secretion of testosterone in testes
Stimulates interstitial cell development in testes
Cells of the anterior pituitary (3)
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__________________- “lacto” = milk
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Secrete prolactin (PRL)
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initiating milk production in mammary glands
__________________ - “cortico” = rind or bark
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Secrete adrenocorticotropic hormone (ACTH) or
corticotropin
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Stimulates the adrenal cortex to secrete glucocorticoids
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Ex.) cortisol
Some corticotrophs - remnants of pars intermedia secrete
melanocyte stimulating hormone (MSH)
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Role unclear
May affect brain activity
 levels cause skin darkening
Negative feedback – corticotrophs
7 Anterior pituitary hormones & what they
stimulate
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hGH- stimulates liver, muscle, cartilage,
bone, & others to synthesize & secrete IGFs
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IGF - promote body cell growth, protein synthesis,
tissue repair, lipolysis &  blood glucose
TSH- stimulates synthesis & secretion of
thyroid hormones by thyroid gland
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T3 and T4 -  BMR, stimulate protein synthesis, 
use of glu & f.a. for ATP syn, lipolysis, cholesterol
secretion,  body growth, development of NS
Anterior pituitary hormones (2)
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FSH- follicle stimulating hormone:
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♀- initiate _____________________, induce
ovarian secretion of ________________
♂- stimulates testes to ____________________
LH- luteinizing hormone
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♀- stimulates secretion of _______________ &
__________________, ______________, &
___________________________________
♂ stimulates ___________________ production
Anterior pituitary hormones (3)
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PRL - promotes milk secretion by mammary
glands
ACTH –
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stimulates secretion of ___________________
(for glucose metabolism) by adrenal cortex
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____________________
MSH- exact role unknown, may influence
brain activity, when present in excess can
cause darkening of skin
2 Posterior pituitary hormones, table 18.5
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____________________ (OT)
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stimulates uterine smooth muscle contraction during
childbirth
stimulates contraction of myoepithelial cells in mammary
glands  milk ejection
Pitocin is synthetic form
_______________________ (ADH) or vasopressin
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Anti = against, dia= throughput, ouresis = urination
conserves body water by decreasing urine volume
decrease water loss thru perspiration
raises bp by constricting arterioles
Thyroid hormones, table 18.6 & fig 18.10
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T3 (_________________) and T4 (____________)
 BMR
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Stimulate synthesis of Na+/K+ pump
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↑ lipolysis & enhance cholesterol excretion in bile
Enhance actions of catecholamines (NE and E)
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↑ ATP production ↑ more heat ↑ body temp: calorigenic
Stim protein synthesis &  glucose & fa use to make ATP
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↑ O2 consumption, metabolism of carbs, fats, protein ↑
↑ heart rate, ↑ b.p.
Accelerate body growth (w/ hGH & insulin)
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contribute to development of nervous & skeletal systems
Also a hormone produced in the thyroid:
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__________________ (CT)- parafollicular C
cells of the thyroid produce it
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lowers blood levels of calcium & phosphates
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Inhibits bone reabsorption by osteoclasts & accelerating
uptake of calcium & phosphates into bone matrix
High blood calcium levels stimulate secretion
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(low blood calcium levels inhibit secretion)
Formation, storage & release of T3 & T4,
figures 18.11 and 18.12
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Thyroid = only gland that stores large
quantities of its secretory product
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100 day supply in colloid
Figure 18.11 shows synthesis
Figure 18.12 shows control of secretion:
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TRH from hypothalamus  anterior pituitary
causes releases TSH  thyroid gland causes
release of T3 & T4  negative feedback inhibition
of both TRH & TSH
Thyroid problems
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Deficiencies in thyroid hormones during fetal
development, infancy or childhood causes:
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______________________ symptoms
include:
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Severe mental retardation
Stunted bone growth
↑ heart rate, ↑b.p.,  force of heart beats
Removal of thyroid- __________________
_____________________ because cannot
utilize calorigenic effect
Parathyroid gland hormones
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_______________________ (PTH) Specifically works by  # & activity of _____________
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 bone resorption, releasing ionic Ca2+ & phosphates
In the _________________:
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Slows Ca2+ & Mg2+ loss to urine
 phosphate loss from blood to urine
promotes formation of calcitriol by kidneys
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Calcitriol = active form Vitamin D
 absorption rate of dietary Ca2+ , Mg2+ ,& phosphates
Blood Ca2+ directly controls _______________ (from
thyroid gland) & PTH secretion via negative feedback
Adrenal glands = suprarenal glands
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CT capsule cover, highly vascularized (like thyroid)
Adrenal ___________ – 80-90% of gland, peripheral
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Produces steroid hormones essential for life
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Loss would lead to death due to dehydration &
electrolyte imbalance (few days to week) unless
HRT
Adrenal ____________ – centrally located
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Produces 3 _____________________
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Norepinephrine
Epinephrine
Dopamine (small amount)
Modified sympathetic ganglion of the ANS
Adrenal cortex hormones
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______________ (mainly aldosterone) - affect
mineral homeostasis, in zonula glomerulosa
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↑ blood levels of Na+ & water
 decrease blood levels of K+
_______________________ promotes excretion of
H+ in urine
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Removing acids  preventing acidosis
Adrenal cortex hormones
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__________________ -95% _____________ =
hydrocortisone, corticosterone, & cortisone, zona
fasciulata
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affect glucose homeostasis,
Regulate metabolism & resistance to stress
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↑ protein breakdown (except in liver)
stimulate gluconeogenesis in liver & lipolysis
provides resistance to stress
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Glucose at liver provides source of ATP to combat stresses:
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Exercise, fasting, Symp NS, temp∆, high altitude, bleeding,
infection, surgery, trauma, disease
Raise bp- advantageous during blood loss
 inflammation & depress immune responses
Sex hormones from adrenal cortex
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________________-(mainly dehydropiandrosterone
or DHEA), small amounts of weak androgens that
have masculinizing effects, in zona reticularis
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assist in early growth of axillary & pubic hair in both sexes
Contributes to pre-pubertal growth spurt
After puberty in males androgen- testosterone is released in
greater quantities by testes
in females, contribute to libido & are converted to estrogens by
other tissues
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after menopause all estrogens come from this source
Adrenal medulla hormones
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Adrenal medulla develops just as other sympathetic
ganglia but the cells secrete hormones- called
chromaffin cells
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Innervated by symp preganglionic neurons that release Ach
Both hormones are not essential for life but intensify
________________ responses in other parts of body
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____________ = adrenaline, 80% of medullary cells secrete
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Cortisol induces secretion of an enzyme to convert NE to E
_________________ = noradrenaline, 20% of medullary
cells secrete because they lack converting enzyme
Pancreatic Islet hormones
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_____________ – pan = “all,” creas = “flesh”
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Endocrine and exocrine
99% of cells arranged in acini- clusters that
produce digestive enzymes that flow thru ducts to
the GI tract
Scattered among acini are clusters of endocrine
tissue- _______________________ or islets of
Langerhans
Abundant capillary supply
Islet cell types
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Alpha cells = A cells - 17% of islets cells
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Secrete _________________ –  blood glucose
by accelerating breakdown of glycogen in liver
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Converts other nutrients into glucose at liver
Releases glucose into blood
Beta cells = B cells – 70% of islet cells
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Secrete _______________- ↓ blood glucose by
accelerating transport of glucose into cells
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Converts glucose into glycogen
Decreasing glycogenolysis & gluconeogenesis
Increases lipogenesis & stimulates protein synthesis
Islet cell types (2)
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Delta cells = D cells – 7% of islet cells
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Secrete ________________ = growth hormone
inhibiting hormone
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paracrine effect to inhibit insulin & glucagon release
slow absorption of nutrients from GI tract
F cells – remainder of pancreatic islets
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Secrete ____________________- inhibits
somatostatin secretion
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Inhibits gall bladder contraction
Inhibits digestive enzyme secretion by pancreas
Regulation of insulin and glucagon
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____________________ - most important regulator
but several hormones & NT regulate too
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________________ secretion stimulated by:
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hGH and ACTH
Ach stimulates insulin secretion
Amino acids: arginine & leucine
GIP- glucose dependent insulinotropic peptide- released when
glucose in GI tract
________________ secretion stimulated by:
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 Symp NS activity
Rise in blood aa if glucose low (mainly protein meal)
Ovaries
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table 18.10
Produce gametes
Produce steroid hormones (work with FSH & LH):
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__________________ - β-estrodiol, estrone, and estriol
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___________________ –
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prepare endometrium of uterus for implantation
mammary glands- milk production
___________________ –
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 flexibility of pubic symphysis during pregnancy
Dilate cervix during labor & delivery
___________________ – inhibits secretion of FSH
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development of oocytes
maintain repro structures
appearance of 2° sex characteristics
Testes
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table 18.10
Produce gametes
Produce steroid hormones
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_________________ –
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descent of testes
spermatogenesis
controls growth of development of male repro organs
appearance of 2° sex characteristics
body growth
_________________ – inhibits secretion of FSH
Diseases and disorders
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Pituitary Gland disorders:
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hGH disorders: figure 18.22
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Hyposecretion:
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_____________________________ - during growth years slows
bone growth & epiphyseal plates close before normal height, body
proportions remain childlike

Treatment- administer hGH during childhood
Hypersecretion:
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_______________________ – during childhood, abnormal ↑ long
bone length, tall but proportions normal
________________________ – during adulthood, hGH cannot
lengthen long bones but hands, feet, cheeks, jaws thicken and
enlarge; eyelids, lips, tongue, & nose enlarge; skin thickens &
develops furrows
Disease and disorders (2)
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_____________________ – most common
abnormality assoc w/ the posterior pituitary
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Due to defects with ADH receptors or inability to secrete
ADH
Common symptom – excretion of large volumes of urine
resulting with dehydration and thrist
 Bed wetting common in children
 Person may die of dehydration if deprived from water for
a day or more
Treatment – HRT for _____________, ________________
may involve diet restrictions (restriction of salt) depending
upon details and specifics of kidney dysfunction
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Thyroid gland disorders:
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Hyposecretion:
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_________________________ (previously cretinism) present at birth, devastating if not prompt treatment
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Severe mental retardation
Stunted bone growth
 Treatment- oral thyroid hormone treatment- birth thru life
______________ – in adulthood, 5x more common in ♀
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Edema causes facial tissue to swell and look puffy
Slow h.r.,  body temp, sensitivity to cold, dry hair & skin
Muscular weakness and general lethargy
Tendency to gain wgt easily
Brain has matured  no retardation, but might be less alert
 Treatment = oral thyroid hormones to  symptoms
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Thyroid gland disorders (2):
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Hypersecretion:
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_____________ –most common, 7-10X more ♀ < 40 yrs
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Autoimmune disorder, Ab mimic TSH
Enlarged thyroid (2-3x normal size)
Peculiar edema behind eyes = exophthalmus
 Treatment – partial or full thyroidectomy, radioactive
iodine to destroy thyroid tissue, antithyroid drugs
_____________ – enlarged thyroid gland
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Assoc w/ hyperthyroidism, hypothyroidism, or euthyroidism
(“good,” normal secretion)
Dietary intake of iodine may be inadequate
 thyroid hormone in blood stimulates TSH  enlarge

Parathyroid gland disorders:

___________________ – too little PTH
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Deficiency of blood Ca2+  neurons & muscle fibers to
depolarize and produce spontaneous AP
Twitches, spasms, tetany
Leading cause: damage to parathyroid glands or their
blood supply during thyroidectomy
____________________– elevated PTH
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Often due to tumor on one of the glands
Excessive reabsorption of bone matrix
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Raises blood calcium and phosphates, bone soft and easily
fractured.
 ↑ blood Ca2+ promotes kidney stones
Fatigue, personality changes, lethargy

Adrenal gland disorders:

Hypersecretion of cortisol: ______________________
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adrenal gland tumor or tumor where ACTH is secreted
stimulating excess cortisol
Breakdown of muscle protein, redistribute body fat
Moon face, buffalo hump, hanging abdomen
↑ cortisol  hyperglycemia, osteoporosis, weakness,
hypertension, ↑ risk of infection,  stress resistance, mood
swings
Hyposecretion of glucocorticoids & aldosterone:
___________________________ (leads to ↑ K+,  Na+)

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most cases = autoimmune disorders: Ab block or destroy
binding of ACTH to its receptors, bacteria.
symptoms: appear usually after 90% of adrenal cortex is
destroyed– mental lethargy, anorexia, nausea, vomitting, wgt
loss, hypoglycemia & muscle weakness

Treatment – replace glucocorticoids, mineralocorticoids, Na+

Pancreatic Islet disorders:

_____________________- most common
endocrine disorder, inability to produce insulin

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4th leading cause of death in US  cardio damage
Unavailable insulin  ↑ glucose in blood spills into urine
_________– person’s immune system destroys beta
cells, AKA insulin dependent diabetes mellitus (IDDM)
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Usually people under 20, persists thru life
Time of symptoms- 80-90% beta cells destroyed
Cardio problems, vision loss-cataracts, kidney problems
_________ – target cells less sensitive to insulin due to
down regulation of receptors
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> 90% of cases, obese & over 35
Control by diet, exercise, weight loss, drug stim insulin

Pancreatic Islet disorders (2):

_____________– diabetic injects too much insulin

Symptom – _______________-  blood glucose level
due to excess insulin causing uptake


Results in secretion of epinephrine, glucagon, hGH
 Anxiety, sweating, tremor, ↑ h.r., hunger, weakness
Brain cell deprived of glucose  mental disorientation,
convulsions, unconsciousness, and shock
 Death can result if glucose level is not raised